A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 6645-00-881-9978
NSN 5965-01-528-6453
NSN 6320-01-592-6248
NSN 5910-00-120-1692
NSN 6130-01-628-8377
NSN 5985-01-280-4835
NSN 6145-01-611-0413
NSN 4140-01-006-3324
NSN 6110-00-855-5695
NSN 5998-01-103-5593
NSN 6240-00-270-6824
NSN 5998-01-064-2267